Following this enlightening path, we will proceed to explain the reason HKB”H commanded Aharon to also bear the names of the twelve shevatim on the Choshen over his heart. As explained, the twelve names of Yisrael that he carried on his two shoulders were a remembrance before Hashem that since Aharon was willing to shoulder the blame for Yisrael, he was worthy to be the Kohen Gadol to provide atonement for the “cheit ha’eigel” and the cheit of avodah-zarah in general. This constituted a process of "סור מרע"—avoiding negative, bad behavior. Aharon, however, also was privileged to bestow the Berachos of Birkas Kohanim upon Yisrael—a process of ״עשה טוב״—acting in a positive, good manner. This is evident from the following pesukim (Bamidbar 6, 22): "וידבר ה' אל משה לאמר, דבר אל אהרן ואל בניו לאמר, כה תברכו את בני ישראל אמור להם, יברכך ה' וישמרך, יאר ה' פניו אליך ויחונך, ישא ה' פניו אליך וישם לך שלום".
And Hashem spoke to Moshe, saying: Speak to Aharon and his sons, saying, “Thus shall you bless Bnei Yisrael. Say to them, ‘May Hashem bless you and protect you. May Hashem shine His Countenance upon you and find favor with you. May Hashem lift His Countenance toward you and bring you peace.’”
It appears that we can explain the reason that Aharon and his offspring merited bestowing the Berachos of Birkas Kohanim on Yisrael based on the following Midrash (Bamidbar Rabbah 11, 7): "רבי שמעון בן חלפתא אמר, גדול שלום שאין כלי מקבל ברכה אלא שלום, שנאמר ה' יברך את עמו בשלום, אף בברכת כהנים אחר כל ברכות סיימן בשלום וישם לך שלום, לומר שאין הברכות מועילות כלום אלא אם כן שלום עמהם". Rabbi Shimon ben Chalafta said: Great is shalom; for there is no vessel that receives berachah other than shalom, as it says (Tehillim 29, 11): “Hashem will bless His people with shalom.” Even in Birkas Kohanim, after all of the Berachos, He concludes them with shalom: “And bring you shalom”—to convey that the Berachos are meaningless unless they are accompanied by shalom.
This teaches us that all of the Berachos are of no value if shalom does not prevail among the people of Yisrael. Without shalom, it is analogous to a person who goes to draw water from a well with a bucket that is full of holes and cracks. Clearly, any water that he draws from the well will spill out onto the ground. Therefore, HKB”H concludes Birkas Kohanim with the berachah of shalom: "וישם לך שלום"; because we have an important principle (Berachos 12a): "הכל הולך אחר החיתום"—everything follows the conclusion (of the berachah). So, if shalom prevails among Yisrael, then they possess the vessel necessary to retain all of the Berachos contained in and forthcoming from Birkas Kohanim.
This explains magnificently why HKB”H chose Aharon and his descendants to bless Yisrael in this manner. For, the Gemara teaches us a fundamental principle (B.M. 107b): "קשוט עצמך ואחר כך קשוט אחרים"—first correct yourself and only afterwards correct others. In other words, in order to bestow the blessing of shalom upon others, one must first have achieved that midah to perfection in himself. Now, Aharon was the personification of the midah of shalom, as we are taught in the Mishnah (Avos 1, 12): "הלל אומר, הוי מתלמידיו של אהרן, אוהב שלום ורודף שלום, אוהב את הבריות ומקרבן לתורה"—Hillel says: Be among the disciples of Aharon—love peace and promote peace, love your fellow creatures and bring them closer to Torah.
Furthermore, we have an explicit passuk extolling the virtue of Aharon (Bamidbar 20, 29): "ויראו כל העדה כי גוע אהרן ויבכו את אהרן שלשים יום כל בית ישראל"—the entire assembly witnessed that Aharon had perished; they wept for Aharon thirty days—the entire house of Yisrael. Rashi comments: Everyone grieved over Aharon’s death, both men and women alike, since he was the ultimate peacemaker—he promoted shalom and amity among disputants, and between husbands and wives. Therefore, it was only fitting for Aharon HaKohen, the epitome of shalom, to be the agent to bestow the Berachos of Birkas Kohanim on Yisrael—the Berachos that culminate with the berachah of shalom—Aharon’s trademark.
